NEW YORK -- Autotote, the company whose computer security has been questioned during the Breeders' Cup pick six investigation, is installing a system to monitor the activities of people with access to its betting network, according to a letter that the company has sent to racetracks.

The system, which is manufactured by a Canadian company, eSuccess Solutions Inc., will "have an alarm function that will immediately notify specific personnel of any attempted tampering or alteration of data," according to the letter, which was signed by Lorne Weil, the chairman of Autotote's parent company, Scientific Games, and Brooks Pierce, the president of Autotote. The system will be installed at all Autotote sites in 30 days, said the letter, which was dated Nov. 15.

Autotote officials declined to comment on the letter on Friday. Autotote, the country's largest totalizator company, processes 65 percent of the bets in the U.S.

According to Alan Ahacs, vice president of eSuccess, the security systems will independently receive all the betting data that Autotote's systems receive, including the precise structure of betting tickets. The security system will calculate its own betting payouts based on that data, and check the payouts against the Autotote system for any inaccuracies, including the alteration of any wagers, Ahacs said.

"It allows any regulator or racetrack to have an independent view to make sure all the rules are being followed," Ahacs said.

Since the pick six investigation was launched on Oct. 27, concerns have been raised by racing and wagering experts about the security controls at Autotote and other tote companies, which link hundreds of betting sites. Some racing officials have complained that the current tote system is outdated and inefficient.

Software already used in CanadaA spokeswoman for Autotote said on Friday that the new security system was not yet in place at any site in the U.S., although the Canadian Pari-Mutuel Agency installed the system earlier this year to monitor bets at all Canadian racetracks. Autotote handles wagers from some Canadian tracks, including Woodbine and Hastings Park.

Autotote fired Chris Harn, a 29-year-old senior programmer, on Oct. 31 after conducting an internal investigation into the Breeders' Cup pick six ticket. On Tuesday, Harn surrendered to the F.B.I. with two former fraternity brothers, Derrick Davis and Glen DaSilva, both 29.

In a criminal complaint filed against the three, federal prosecutors allege that Harn altered pick six and pick four tickets that were placed by Davis and DaSilva through a telephone-betting account at Catskill OTB in New York. The complaint said that Harn had access to data at Catskill's hub in Poughkeepsie, which is run by Autotote.

Several racing officials have said that lack of security controls at Autotote have presented difficulties to investigators who are attempting to gather evidence that the tickets might have been altered. Before Harn was fired, some officials at Autotote had said that they believed the disputed tickets were legitimate.

The letter says that Autotote has hired Kroll Inc., a security consulting company, to review its computer systems, security controls, and operating procedures. The letter says that Autotote plans to install software at its wagering sites that will change the way pick six and pick four data is transmitted by Nov. 29, based on a recommendation made by the National Thoroughbred Racing Association's working technology task force.

Pick six and pick four tickets have been under scrutiny because the betting numbers of the horses used are not transmitted to the national hub until after the next-to-last race in the sequence is run, creating a window of opportunity for someone with access to tote computers to alter tickets.

NYRA alters pick six rulesOn Friday, the New York Racing Association announced that it will no longer allow pick six players to make an alternate selection in case of a late scratch. Players who have picked a scratched horse will receive the betting favorite, NYRA officials said.

According to Bill Nader, a NYRA vice president, the use of alternates had to be canceled to comply with the NTRA recommendation for pick six bets. The NTRA recommendation was to ask sites to send information on live pick six tickets into the national pool after each race in the bet was run. According to tote experts, tickets that had alternate selections were not being transmitted until all six races in the bet had been run.

California tracks also allow players to select alternate selections for the pick six. Rick Baedeker, the president of Hollywood Park, said on Friday that the issue of alternates "had not yet come up, but that does not mean it won't be something we'll have to address in the future."